Thread-cutting tool with automatically retirable chasers



June 12, l95l 2,557,040

THREAD-CUTTING'TOOL WITH AUTOMATICALLY-RETIRABLE CHASER Filed Aug. 51', 1948 R. M. STRICKLAND 4 Sheets-Sheet 1 June 12, 1951 STRICKLAND 2,557,040

THREAD-CUTTING TOOL WITH AUTOMATICALLY-RETIRABLE CHASER Filed Aug. 51, 1948 4 Sheets-Sheet 2 (u0//r fi/V/JMVG 607 June 1951 R. M. STRICKLAND 2, ,0

THREAD-CUTTING TOOL WITH AUTOMATICALLY-RETIRABLE CHASER Filed Aug. 31, 1948 4 Sheets-Sheet J ne 12, 1951 R. M. STRICKLAND I 2557040v THREAD-CUTTING TOOL WITH AUTOMATICALLY-RETIRABLE CHASER Filed Aug. 31, 1948 4 Sheets-Sheet 4 Patented June 12, 1951 THREAD-CUTTING TOOL WITH AUTO- MATICALLY RETIRABLE CHASERS Royce M. Strickland, New Haven, Conn., assignor, by mesne assignments, to Greenfield Tap and Die Corporation, Greenfield, Mass, at corporation of Massachusetts Application August 31, 1948, Serial No. 46,966

10 Claims. 1

The present invention relates to improvements in thread-cuttin tools and relates more particularly to improvements in thread-cutting tools having automatically-retirable chasers, i. e., thread-cutting tools in which the chasers may be automatically retired out of engagement with the work after the formation of the desired thread, to thus enable the tool and work to be separated in an axial direction without requiring an unthreading operation.

One of the main objects of the present invention is to provide a superior thread-cutting tool of the character referred to, which is of versatile utility, and in which the elements are constructed and arranged with compactness and with minimum likelihood of derangement despite hard use. Another object of the present invention is to provide a superior thread-cutting tool having automatically-retirable chasers and in which simple, reliable and convenient means is provided whereby the tool may be utilized for both roughing and finishing cuts with minimum delay between operations.

A further object of the present invention is to provide a superior tool of the character referred to having means whereby it may be rapidly set selectively for either roughing or finishing cuts and in which the operation of the said means is effected automatically after the completion of one type of out.

With the above and other objects in view, as will appear from the following considered in conjunction with the accompanying drawings, the present invention involves certain unique construction and arrangement of parts, a preferred embodiment of which will be hereinafter described.

In the accompanying drawings, in which certain modes of carryin out the present invention are shown for illustrative purposes:

Fig. l is a view in front elevation of a selfopening die-head embodying the present invention and shown as set in readiness for a roughing threading operation and in readiness for being tripped;

Fig. 2 is a top or planview thereof;

Fig. 3 is a transverse sectional View taken on the line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 3 but showing the parts set to efiect a full finishing cut;

Fig. 5 is a broken view in longitudinal section taken on the line 5-5 of Fig. 3;

Fig. 6 is a fragmental sectional view taken on the line 6-6 of Fig. 3;

Fig. '7 is a broken longitudinal sectional view taken on the line 1-7 of Fig. 3;

Fig. 8 is a similar view but taken on the line 88 of Fig. 3;

Fig. 9 is a broken longitudinal sectional View taken on the line 99 of Fig. 3;

Fig. 10 is a perspective view of the adjustingring, detached;

Fig. 11 is a similar view of the cut-selecting lever;

Fig. 12 is a perspective view of one of the retaming-plates;

Fig. 13 is a similar view of the latching-plate;

Fig. 14. is a broken view in longitudinal section taken on the line l4l4 of Fig. 3;

Fig. 15 is a perspective view of the unit comprising the retaining-plate and latch-lever and viewing the same mainly from the front face thereof;

Fig. 16 is a similar but smaller scale view and viewing the unit mainly from the rear;

Fig. 17 is a perspective view of the chaser-carrying member, viewing the same mainly from the rear; and

Fig. 18 is a perspective view of the latch-lever with its latching-pin and viewing the same main- W from the front.

The particular self-opening die-head illustrated in the accompanying drawings for purposes of making clear a preferred embodiment of the present invention, includes a mounting-member generally designated by the reference character 20. The said mounting-member includes a tubular shank 2|, a head-flange 22 at the forward end of the said shank, a head-plate 23 secured against ly beyond the head-plate 23 in coaxial relationship with respect to the tubular shank 2|.

The tubular guide-portion 24 of the mountingmember 20 has at its rear end a flange-like head 25 which is accommodated in a forwardly-opening recess '26 formed in the forward face of the head-flange 22. The said guide-portions may be brazed or otherwise rigidly secured to the headplate 23-.

The head-plate 23 above referred tois rigidly but removably coupled to the head-flange 22 by means of two (more or less) socket-head screws 2'l-'2'i, as is indicated in Figs. 1 and 2 From the foregoing it will be apparent that the elements 2| to 25 inclusive of the mountingmember 20 are organized together as a unitary structure, and the fact that certain of the said elements are made separate from others is for purposes of convenience of manufacture and interchangeability of parts.

The head-flange 22 and the head-plate 23 of the mounting-member are of substantiallyrectangular form in elevation, and the sockethead screws 2T2| are respectively located at diametrically-opposite corners thereof, as is indicated in Fig. 1. Rigidly mounted in the remaining two corners of the head-flange 22 and head-plate 23 are two coupling-studs 28-28 which project forwardly beyond the forward face of the said head-plate 23 and extend with a sliding fit into bushings 2929 (Fig. 8) mounted in a retaining-plate 30.

The retaining-plate 30 above referred to is rigidly attached to the rear portion of a chasercarrying member 3| by means of two (more or less) screws 32-32, one of which latter is shown in elevation in Fig. '7 and both of which are shown in transverse section in Figs. 3 and 4.

At its forward end, the chaser-carrying member 3| is formed with an integral flange-like head 33 in which is formed four (more or less) substantially-radial guide-grooves 34 equidistantly spaced from each other in a circumferential direction and intersecting both the outer and inner peripheries of the said head 33, as well as the front and rear faces thereof, as is especially well shown in Figs. 8 and 17. Mounted for substantially-radial reciprocating movement in each of the guide-grooves 34 just referred to is one of four similar thread-cutting chasers 35 each provided at its inner end with the usual thread-cutting teeth 36. Each of the said chasers is formed in its rear face with a rearwardly-opening substantial- I ly-transverse but slightly-inclined notch 31.

The notch 31 in each of the chasers 35 is adapted to receive one of four similar cam-lugs 38 each of which is inclined with respect to the periphery of the chaser-carrying member 3| as is apparent in Fig. 1. The said cam-lugs 38 are formed integral with and project forwardly from the front face of an oscillating chaser-operating ring or member 39 turning upon the outer periphery of the rear portion of the chaser-carrying member 3| in a position wherein it is confined against appreciable movement in an axial direction between the flange-like head 33 of the chasercarrying member 3| and the retaining-plate 30 before referred to.

As before noted, the unit comprising the retaining-plate 3B and chaser-carrying member 3| (as well as the parts carried thereby) has capacity for slight axial movement with respect to the mounting-member movement is guarded against by the couplingstuds 28-28. The said unit, however, is yieldingly restrained against both relative forward movement and relative rearward movement in a manner as will be presently described.

For the purpose of yieldingly holding the chaser-carrying member 3| and the parts carried thereby against movement in a forward direction, there are provided two helical retracting-springs 404|l, both of which are shown in transverse section in Figs. 3 and 4 and one of which is shown in side elevation in Fig. 5. Each of said retracting-springs is accommodated within one of two sockets 4|4| formed partly in the rear portion of the chaser-carrying member 3| and partly in the retaining-plate 30, as is especially well shown in Fig. 5. Each of said retracting-springs encircles the forward portion of one of two corresponding double-headed studs 42-42 secured at their rear ends in the head-plate 23. As is indi- 20, though relative rotary 4 cated in Fig. 5, a given one of the studs 42 is releasably secured to the head-plate 23 by means of a set-screw 43.

For the purpose of yieldingly restraining the rearward movement of the chaser-carrying member 3| and the parts carried thereby with respect to the mounting-member 23, there are provided two (more or less) buffer-springs 4444, both of which are indicated in Figs. 3 and 4 and one of which is shown in elevation in Fig. 14. By reference to Fig. 14 it will be seen that a given bufferspring 44 is located in a rearwardly-opening socket 45 formed in the chaser-carrying member 3|. A given buffer-spring 44 just referred to is seated at its forward end against the bottom or end of its complemental socket 45 and at its rear end seats against the forward end of a plunger 46 mounted for limited movement in a direction paralleling the central-longitudinal axis of the structure, in the retaining-plate 30. The rear end of the given plunger 46 is seated against the forward face of the head-plate 23.

From the foregoing it will be seen that normally the rearward draft exerted upon the chaser-carrying member 3| (and the parts carried thereby) by the retracting-springs 4340 and the forward urge exerted on the said chaser-carrying member by the buffer-springs 4444 will come to a condition of balance when the said chaser-carrying member is free of other restraint against axial movement.

As before pointed out, the retaining-plate 33 is coupled to the mounting-member 26 (with capacity for axial movement) by the coupling-studs 2828. In order to rigidly couple the retainingplate 30 to the chaser-carrying member 3| against relative turning movement, the said retainingplate is formed with two laterally-spaced-apart chord-shaped coupling-ribs 41-41 (Figs. 3, 4 and 15) which are adapted to snugly receive between them a relatively-wide coupling-rib 48 formed on the rear portion of the chaser-carrying member 3|, as is especially well indicated in Fig. 17.

In its rear face, the chaser-operating ring 33 is formed with a rearwardly-opening annular recess 49 in which is mounted with capacity for adjustment in a circumferential direction, an adjusting-ring 50 which is especially well shown in Fig. 10. Projecting rigidly forwardly from the adjusting-ring 5|! is an adjusting-stud 5|, as is especially well shown in Figs. 9 and 10. The said adjusting-stud is adapted to move in a circumferential direction in an arcuate recess 52 formed in the chaser-operating ring 39 and located forwardly of the annular recess 49 and opening rearwardly into the latter.

For the purpose of bodily shifting the adjusting-ring 50 in a circumferential direction relative to the chaser-operating ring 39, the said chaser-operating ring has threaded into it two substantially-tangential adjusting-screws 53S3 (Fig. 3) which engage with the opposite sides of the adjusting-stud 5| projecting forwardly from the said adjusting-ring 50.

Also located in the annular recess 49 in the rear of the chaser-operating ring 39 and secured against the rear face of the adjusting-ring 50, is an arcuate latching-plate 54 which may be moved in a circumferential direction with respect to the adjusting-ring 5G for purposes as will hereinafter appear. The latching-plate 54 is held in place against the rear face of the adjusting-ring 50 by two corresponding arcuate retaining-plates 55-55 which are rigidly secured in any suitable manner to the rear face of the said adjusting- 5, ring 50. The respective opposite ends' of the latching-plate 54 are provided with oppositelyextending retaining-fingers 5856 fitting with a sliding fit into the adjacent notched ends respectively of the retaining-plates 55-45.-

At the junction of one of its fingers 56 with the main body of the latching-plate 5 1 there is provided a latching-abutment 5! which is adapted to be releasably engaged by a latching-pin, in the manner as will hereinafter appear.

For the purpose of turning the chaser-operating ring 39 in the direction (clockwise in 1- counterclockwise in Figs. 3 and 4) necessary to cause its inclined cam-lugs 38 to retire the chasers 35, there is provided a helical chaserretracting spring 58. The said spring is located in the annular recess 49 in the rear face of the chaser-operating ring 39 against the rear face of the adjusting-ring 50. One end of the chaserretracting spring 58 thrusts against the adjacent one of the two retaining-plates 55, while its opposite end'thru'sts against the stud 59 projecting forwardly from the retaining-plate 30, as is especially well indicated in Fig. 5.

The chaser-retracting spring 58 is retained in place against lateral movement rearwardly out of the annular recess 49 in the chaser-operating ring 39, by an arcuate retaining-lip 60 extending rearwardly from the adjusting-ring 55).

For the purpose of releasably holding the chaser-operating ring 39 against turning movemerit under the urge of the chaser-retracting spring 5'8 there is provided a latching-pin or abutment 6| which is adapted to releasably engage with the latching-abutment 51 of the latching-plate 54 before referred to.

V Thelatching-pin 6| above referred to projects forwardly from and is rigidly mounted in the intermediate portion of a latch-lever 82 which is accommodated in a radial groove 62a formed in the rear face of the retaining-plate 30. A retaining-pin 63 is mounted in the latch-lever 62 and its respective opposite ends loosely fit into notches 63a63a formed in the rear face of the retaining-plate 30, as may be seen by reference to Fig. 16. The said latch-lever 62 is adapted to pivot upon its forward inner corner so that its outer end may swing forwardly and backwardly respectively to engage the latching-pin 6| with and disengage the same from the latching-abutment 51 of the latching-plate 54,. all in the manner as will more fully hereinafter appear.

For the purpose of yieldingly holding the outer end of the pivotal latch-lever 62 in a forward or latching position, there is provided a doubleheaded spring-plunger 64 (Figs. 9 and 1-5) having its rear head seated against the rear of the latch-lever 62 and having its forward portion encircled by a latch-spring 65 located in a recess 68 in the rear portion of the chaser-carrying member 3|. The said latch-spring presses at its front end against the front head of the springplunger 64 and presses at its rear end against the front face of the retaining-plate 30.

The outer end of the latch-lever 62 is formed with a clearance-passage 61 freely receiving the tubular rear portion of a tripping-nut 68 which is threaded onto the forwardly-projecting stem 69 of a tripping-screw 10, as is shown in Fig. 9. The tripping-screw 10 is adapted to reciprocate in a clearance-passage H formed in the headplate 23 of the mounting-member 26. The said tripping-screw is formed with a diametrical longitudinally extending clearance slot 12 adapted to receive av removable and replaceable 6 couplihg pin 13 which is mounted in the headplate 23. As is indicated in Fig. 9, the trippingscrew is also formed with a coupling-passage 14 adapted to snugly receive the coupling-pin 13 when the tripping-screw 10 is turned ninety degrees from the position in which it is shown in Fig. 9, to thereby interlock the said trippingscrew with the head-plate 23 against movement withrespect thereto in an axial direction.

Threaded onto the forward end of the stem 69 of the tripping-screw This a tripping-head 15 which extends through and is adapted to reciprocate in a bracket 16 rigidly attached to the flange-like head 33 of the chaser-carrying member 3!, as is shown in Figs. 1, 2 and 9.

For the purpose of enabling the user of the selfopening die-head shown in the accompanying drawings, to readily and rapidly select the desired depth of out, there is provided a cut-selecting lever generally designated by the refer? ence character 7! which, in the main, may be formed of plate metal. The said cut-selecting lever is formed at its inner end with a circularlycontoured bearing-portion 18 carrying an eccentrically positioned actuating-stud 79. At its outer end, which projects beyond the periphery of the chaser-operating ring 39, the lever T7 is provided with a ball-like head 80. The said cut-selecting lever projects through an arcuate clearance-slot 11a formed in the ring 39.

A The actuating stud 19 of the cut-selecting lever Ti above referred to projects rearwardly (Fig. 5) from the bearing-portion l3 thereof, which latter is formed in its rear face with a series of three (more or less) detent-pockets 8!, which series is arranged concentrically with respect to the central-longitudinal axis of the actuatingstud 19, as is especially well indicated in Fig. 11. a The bearing-portion 18 of the cut-selecting lever TI is mounted for turning movement in a direction transverse of the die-head structure in a rearwardly-opening bearing-groove 82 (Fig. l9) formed in the rear face of the adjusting-ring 50 and extending in a radial direction. The actuating-stud "i9 projects rearwardly into a cylindrical bearing-opening 83 extending transversely from face to face through the latching-plate 54, as will be apparent by reference to Figs. 5 and 13.

Located adjacent and extending in parallelism with the bearing-opening 83 in the latching-plate 54 is a forwardly-opening recess 84 (Figs. 6 and 13 in which is accommodated a detent-spring 85 and a detent 86 in the form of a. ball. The detent 865 is adapted to be yieldingly pressed into the registering one of the three detent-pockets 85 in the cut-selecting lever H, for purposes as will hereinafter appear. I

To provide for the convenient resetting of the chaser-operating ring 39 after the same has been released to the action of the chaser-retracting spring 58, a resetting-handle 81 is rigidly connected to the said ring so as to project radially therefrom.

OPERATION The self-opening die-head above described is adapted to have its chasers 35 released for out ward retirement out of engagement with the work, by the engagement of the forward face of its tripping-head l5 with any suitable abutment upon the machine in which the die-head is used, or. on the other hand, the said chasers may be re leased by relative axial forward draft exerted on the said chasers by the work being done. ihe operation, therefore, will be described in two phases.

The abutment-tripping of the die-head With the parts positioned as shown in Figs. 1, 2 and 3, the die-head is ready for effecting the threading of a rod, pipe or the like, since the chasers 35 are projected inwardly into their advanced or thread-cutting positions, and the latching-pin 6| by its engagement with the latching-abutment 51 of the latching-plate 1 is serving to rigidly but releasably hold the said chasers in the positions referred to, against the tension of the chaser-retracting spring 58.

The cut-selecting lever 11 is now in the position in which it is shown by full lines in Figs. 1, 2 and 3, so that the chasers 35 are not projected inwardly to their fully advanced position and will, therefore, under the circumstances, make what might be called a roughing cut inasmuch as a subsequent and light finishing cut may be later taken, in a manner as will hereinafter appear.

For convenience of description it may be assumed that the shank 2| of the mounting-member 20 is firmly mounted in the turret of a screwmachine or other suitable holder. It may further be assumed that the work to be threaded is being rotated with respect to the die-head structure, which latter is held against rotary movement but with freedom for axial movement toward and away from the work, in a manner well known in the art.

Under the conditions above referred to, the diehead may be moved axially into engagement with a rotating work-piece (or the work-piece may be advanced axially toward the die-head) to efiect the engagement of the chasers 35 with the work and thus thread the same.

Shortly before the work has been threaded to the desired extent, the forward face of the tripping-head 15 may be caused to engage with a suitable abutment on the machine, whereupon the further forward movement of the said tripping-head and the parts rigid therewith (68, 59 and 16) together with the outer portion of the latch-lever 62 will be halted while the remainder of the die-head structure will continue to move axially forwardly with respect to the work.

Shortly after the start of the occurrence just above described, the latching-abutment 5'! will ride forwardly clear of the forward end of the latching-pin Bl, so that the chaser-retracting spring 58 will be able to assert itself and turn the chaser-operating ring 39 in a clockwise direction as viewed in Fig. l and a counterclockwise direction, as viewed in Figs. 3 and 4.

The described movement of the chaser-operating ring 39 will cause its inclined cam-lugs 38 to effect the retraction or retirement of the chasers 35 out of engagement with the work just threaded. The just-threaded piece of work and the die structure may now be axially separated preparatory to taking a further light finishing-cut or heavy finishing-cut thereon should it be desired to so do. The operator, preparatory to resetting the die-head, may now swing the cut-selecting lever H in a clockwise direction as viewed in Figs. 3 and 4 (counterclockwise as viewed in Fig. 1) into either the light finishingcut position indicated by broken lines in Fig. 3, or into the full finishing-cut position indicated by the broken lines in Fig. 3 or by the similarly marked full lines in Fig. 4.

The described swinging movement of the cutselecting lever I? will shift the arcuate latchingplate 54 slightly in a counterclockwise direction (as viewed in Figs. 3 and 4) relative to th'? ad- 8 justing-ring 50, to thereby advance the latching-abutment 51 in the same direction.

Now, when the chaser-operating ring 39 is turned by means of its resetting-handle 81, the latching-abutment 51 of the latching-plate 54 will be shifted into a position wherein the latching-pin 6| may re-engage with it. When reengaged as just described, it will be latched in a position further in advance of the position in which it was previously latched, to thereby locate the inner ends of the chasers 35 slightly further inwardly than during the previous roughing-cut and in position to take a finishing-cut of a few thousandths of an inch in depth upon the work which has just previously been given a roughing-cut. The movement of the cut-select ing lever 1! into its light finishing-cut position will advance the chasers 35 to a lesser degree than would be the case if the said lever were to be moved into the full finishing-cut" position.

The finishing-cut may be completed in the same manner as that described in connection with the roughing-cut, and in this instance, when the die-head is tripped, the chaser-operating ring 39 will snap in a counterclockwise direction as viewed in Figs. 3 and 4, and by this action automatically snap the cut-selecting lever 11 back into the position indicated by full lines in Fig. 3 for effecting a roughing-cut on a subsequent piece of work. In this manner, the die-head may be automatically reset for effecting a roughingcut on a subsequent piece of work without attention by the operator.

The pull-o1? tripping of the die-head In instances where it is desired to efiect the automatic tripping or release of the die-head by means of the work being threaded, the coupling-pin 13 (shown in Fig. 9) may be removed from the head-plate 23 to thereby release the tripping-screw 10, which latter may be turned ninety degrees so that its cylindrical couplingpassage i4 extends in parallelism with the position which the coupling-pin normally occupies. The coupling-pin now may be reinserted to thereby rigidly couple the entire assembly, comprising tripping-nut 68, tripping-screw i0 and tripping-head l5, rigidly with the head-plate 23.

Under the conditions which will now exist, the tripping-screw 10 and the parts rigidly coupled thereto, will no longer be able to have appreciable relative axial movement with respect to the mounting-member 20.

The die-head with its chasers 35 in their inwardly-extended or thread-cutting positions, may now be advanced axiall toward a workpiece, and shortly before the desired length of thread has been completed, the said advance may be halted. Continued rotary movement of the work-piece will, however, draw forwardly upon the chasers and hence draw forwardly upon the chaser-carrying member 3| and the parts carried thereby, including the chaser-operating ring and the latching-plate 54 carried by the latter. During this interval, however, the tripping-screw Ill will be held stationary by the coupling-pin i3, as will also the outer end of the latch-lever 52 by the action of the tripping-nut 68. The inner end of the latch-lever 62, however, will continue to travel forwardly with the chaser-carrying member 3| and retaining-plate 30. In the described manner, the latch-lever 62 will ultiinately be tilted sufficiently to disengage its latching=pin 6| from the latching-abutment 51 of the latching-plate 54. The chaser-retracting sprin 58 will now assert itself to retract the chasers 35 in the same manner as has been described in connection with the first mode of operation of the die-head.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A thread-cutting tool having automaticallyretirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chastr-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaseroperating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers: spring-means urging the said chaser-operating ring to turn in one direction; an adjusting-ring carried by the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjustingring to adjust the same in a circumferential direction; latch-means releasably holding the said chaser-operating member against movement by the said spring-means, the said latch-means including a first latching-member carried by the said adjusting-ring with capacity for movement with respect thereto under the control of the hereinafter-mentioned cut-selecting lever, and a complemental second latching-member 1novably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; and a cutselecting lever pivotally carried by the said chaser-operating ring and operatively connected to the said first latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers.

2. A thread-cutting tool having automaticallyretirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chasereperating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers: spring-means urging the said chaser-operating ring to turn in one dir ct; an adjusting-ring carried by the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaseroperating member against movement by the said spring-means, the said latch-means including a first latching-member carried by the said adjusting-ring with capacity for movement with respect thereto under the control of the hereinafter-mentioned cut-selecting lever, and a complemental second latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; a cut-selecting lever pivotally carried by the said chaser-operating ring and operatively connected to the said first latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers; and spring-pressed detent-means engaging with the said cut-selecting lever to yieldingly hold the same in a selected position of adjustment.

3. A thread-cutting tool having automaticallyretirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaseroperating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers; spring-means urging thesaid chaser-operating ring to turn in one direction; an adjusting-ring carried by the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjustingring to adjust the same in a circumferential direction; latch-means releasably holding the said chaser-operating member against movement by the said spring-means, the said latch-means including a first latching-member carried by the said adjusting-ring with capacity for movement with respect thereto under vthe control of the hereinafter-mentioned cut-selecting lever, and a complemental second latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; and a cut-selecting lever carried by the said chaser-operating ring and pivoted thereto about an axis extending in substantial parallelism with the centrallongitudinal axis of the tool, the said cut-selecting lever being operatively connected to the said first latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers.

4. A thread-cutting tool having automatically-retirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a Work-piece; a chaser-operating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers; spring-means urging the said chaseroperating ring to turn in one direction; an adjusting-ring carried by the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaser-operating member against movement by the said spring-means, the said latch-means including a first latchingmember carried by the said adjusting-ring with capacity for movement with respect thereto under the control of the hereinafter-mentioned cut-selecting lever, and a complemental second latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; a cut-selecting lever carried by the said chaser-operating ring and pivoted thereto about an axis extending in substantial parallelism with the central-longitudinal axis of the tool, the said cut-selecting lever being operatively connected to the said first latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers; and springpressed detent-means engaging with the said cut-selecting lever to yieldingly hold the same in a selected position of adjustment.

5. A thread-cutting tool having automatically-retirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaser-operating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers, the said chaser-operating ring being provided in its rear face with a circumferentially-curved recess; spring-means urging the said chaser-operating ring to turn in one direction; an adjusting-ring carried by and extending into the recess in the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaser-operating member against movement by the said spring-means, the said latch-means including an arcuate latchingmember carried by the said adjusting-ring with capacity for movement in a circumferential direction with respect thereto under the control of the hereinafter-mentioned cut-selecting lever, and a complemental latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said arcuate latching-member; and a cut-selecting lever pivotally carried by the said chaser operating ring and operatively connected to the said arcuate latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaseroperating ring is latched and thereby selectively determine the cutting position of the said chasers.

6. A thread-cutting tool having automatically retirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaseroperating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers, the said chaser-operating ring being provided in its rear face with a circumferentially-curved recess; spring-means urging the said chaser-operating ring to turn in one direction; an adjustingring carried by and extending into the recess in the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaseroperating member against movement by the said.

spring-means, the said latch-means including an arcuate latching-member carried by the said adjustin-g-ring with capacity for movement in a circumferential direction with respect thereto under the control of the hereinafter-mentioned cut-selecting lever, and a complemental latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said arcuate latching-memher; a cut-selecting lever pivotally carried by the said chaser-operating ring and operatively connected to the said arcuate latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers; and spring-pressed detent-means engaging with the said cut-selecting lever to yieldingly hold the same in a selected position of adjustment.

'7. A thread-cutting tool having automaticallyretirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaser-opcrating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers, the said chaser operating ring being provided in its rear face with a circumierentially-curved recess;

spring-means urging the said chaser-operating ring to turn in one direction; an adjusting-ring carried by and eXtending into the recess in the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latchmeans releasably holding the said chaser-operating member against movement by the said spring-means, the said latch-means including an arcuate latching-member carried by the said adjusting-ring with capacity for movement in a circumferential direction with respect thereto under the control of the hereinafter-mentioned cutselecting lever, and a complemental latchingmember movably carried by another element of the tool and movable into and out of latching engagement with the said arcuate latching-member; and a cut-selecting lever carried by the said chaser-operating ring and pivoted thereto about an axis extending in substantial parallelism with the central-longitudinal axis of the tool, the said cut-selecting lever being operatively connected to the said arcuate latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers.

8. A thread-cutting tool having automaticallyretirable chasers including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaseroperating' ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers, the said chaser-operating ring being provided in its rear face with a circumferentially-curved recess; spring-means urging the said chaser-operring carried by and extending into the recess in the said chaser-operating ring; adjusting-means carried by the said chaser-operating ring and engageable with the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaseroperating member against movement by the said spring-means, the said latch-means including an arcuate latching-member carried by the said adjusting-ring with capacity for movement in a circumferential direction with respect thereto under the control of the hereinafter-mentioned cutselecting lever, and a complemental latching member movably carried by another element of the tool and movable into and out of latching engagement with the said arcuate latching-member; a cut-selecting lever carried by the said chaser-operating ring and pivoted thereto about an axis extending in substantial parallelism with the central-longitudinal axis of the tool, the said cut-selecting lever being operatively connected to the said arcuate latching-member to shift the same relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers; and spring-pressed detent-means engaging with the said cut-selecting lever to yieldingly hold the same in a selected position of adjustment.

9. A thread-cutting tool having automaticallyretirable chasers, including in combination: a

direction to advance and retire the said chasers:

spring-means urging the said chaser-operating member to turn in one direction; latch-means releasably holding the said chaser-operating member against movement by the said springmeans, the said latch-means including a first latching-member carried by the said chaseroperating member with capacity for movement with respect thereto under the control of both the hereinafter-mentioned first adjusting-means and second adjusting-means, and a complemental second latching-member movably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; first adjusting-means carried by the said chaser-operating member and operatively connected to the said first latching-memher to shift the same relative to the said chaseroperating member; and second adjusting-means also carried by the said chaser-operating member said second adjusting-means being operatively connected to the said first latching-member, and adjustable thereby in response to the shifting of said first latching-member by said first adjusting-means, said second adjustingmeans being also operable to shift the said first latching-member relative to the said chaseroperating member to selectively determine the position in which the said chaser-operating member is latched and thereby selectively determine the cutting position of the said chasers.

10. A thread-cutting tool having automatically-retirable chasers, including in combination: a mounting-member; a chaser-carrying member carried by the said mounting-member; chasers carried by the said chaser-carrying member and movable with respect thereto into and out of position to engage with a work-piece; a chaseroperating ring operatively connected to the said chasers and oscillatable in a circumferential direction to advance and retire the said chasers: spring-means urging the said chaser-operating ring to turn in one direction; an adjusting-ring carried by the said chaser-operating ring; first adjusting-means carried by the said chaseroperating ring and operatively connected to the said adjusting-ring to adjust the same in a circumferential direction; latch-means releasably holding the said chaser-operating ring against movement by the said spring-means, said latchmeans including a first latching-member carried by the said adjusting-ring with capacity for movement with respect thereto under the control of the hereinafter-mentionedsecond adjustingmeans, and a complemental second latchingmember movably carried by another element of the tool and movable into and out of latching engagement with the said first latching-member; and second adjusting-means also carried by the said chaser-operating ring said second adjustingmeans being operatively connected to the said first latching-member and adjustable thereby in response to the shifting of said first latchingmember by said first adjusting-means, said second adjusting-means being also operable to shift the said first latching-member relative to the said adjusting-ring to selectively determine the position in which the said chaser-operating ring is latched and thereby selectively determine the cutting position of the said chasers.

ROYCE M. STRICKLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 764,410 Adt July 5, 1904 802,819 Mullaney Oct. 24, 1905 1,044,808 Oster Nov. 19, 1912 1,456,720 Breitenstein May 29, 1923 2,017,764 Mathias Oct. 15, 1935 

